Automatic fuel feed and mixture control



E. E. WICKERSHAM.

AUTOMATIC FUEL FEED AND MIXTURE CONTROL. APPLICATION FILED FEB. 12,1917.

1,395,022. Patented 0st,. 25, N21.

WITNESSES: INVENTOR M Elmer Wzb/ ens/z [4272, MM j Jau/ma through same,

-HTED STATES ATENT OFICE.

ELMER E. WICKERSHAIJL OF STOCKTON, CALIFORNIA, ASSIGNOR TO THE HOLT MANU- FACTURING COMPANY, OF STOCKTON,

FORNIA.

GALIFORNIA, A CORPORATION OF CALI- .AUTOMATIC FUEL FEED AND MIXTURE CONTROL.

Specification of Letters Patent.

Patented Oct. 25, 1921.

T 0 all whom it may concern:

Be it known that I, ELMER E. Wroxnn- SHAM, a citizen of the United States, residing at Stockton, in the county of San Joaquin and State of California, have invented new and useful Improvements in Automatic Fuel Feed and Mixture Qontrols, of which the following is a specification.

This invention relates to an automatic fuel feed and mixture control for carbureters.

@ne of the objects of the present invention is to provide means whereby the vacuum produced in a carburetor when the engine is running may be utilized to elevate fuel to a float chamber in the carbureter. Another object of the invention is to provide means for producing a better mixture of fuel and to automatically regulate the richness of said mixture to conform with varying engine speeds and loads. Further objects will hereinafter appear.

The invention consists of the parts and the construction and combination of parts hereinafter more fully specified and claimed, having reference to the accompanying drawings, in which The figure is a central vertical section through a standard form of Schebler carbureter, showing the application of the invention.

Referring to the drawings in detail, A indicates in general a standard form of Schebler carburetor, 2 the mixing chamber, 3 the bowl or float chamber, 4 the float, 5 the needle valve operated by the float through which fuel or oil is admitted to the float chamber, 6 the spray nozzle, 7 the needle valve controlling the discharge 7 8 the main air intake, 9 the air valve, 10 the adjustable spring which normally holds the valve in closed position, 11 the throttle valve disk, 12 the shaft upon which it is mounted and 13 the throttle lever. Suitably secured in the passage 14 formed between the main air intake 8 and the mixing chamber 2 is a tube 15. The inner end of this tube extends to a position directly in front or" the discharge end of the nozzle 6 while the opposite end connects with the main air intake opening 8.

Forming communication between the float chamber 3 and the mixing chamber 2 is a vent or opening 16, and forming communication between the float chamber and the exterior atmosphere is a vent 17, the opening of which may be adjusted by means of a needle valve 18. lVith the engine running under normal conditions, that is, with the throttle valve partly open, a vacuous condition is established in the mixing chamber of the carbureter. This partial state of vac.- uum is transmitted to the float chamber through the vent 16 and is at all times partially relieved by the air admitted through the vent 17. The amount of vacuum maintained in the float chamber and also in the mixing chamber 2 depends entirely upon the position of the needle valve 18 controlling the opening in the vent 17 and the speed of the engine or the opening of the throttle valve 11. The partial vacuum produced and maintained in the float chamber of the carbureter while the engine is operating is of considerable importance.

First, it permits fuel to be elevated by suction to the float chamber from a tank or other source of supply positioned considerably below the carbureter. Secondly, the vacuum produced and maintained in the float chamber above the fuel level has a tendency to regulate and particularly diminish the fuel flow through the nozzle when the engine is running at a high speed, or, in other words, when the highest possible vacuum is obtained. The advantage of this feature can readily be understood, as it is well known should decrease with increase in engine speed.

In actual operation, when the engine is first started, it is desirable to obtain as rich a mixture of air and fuel as possible. This is obtained by the present arrangement in the following manner:

Turning the engine over either by a crank or self-starter is necessarily comparatively slow and therefore produces a low vacuum or suction. in the manifold or carbureter. All air admitted when starting passes through the tube 15, and, as this is rather constricted in area, it can readily be seen that a high velocity is obtained through said tube, all of .which air is directed past the fuel nozzle. The high velocity of the air in passing by the mouth of the nozzle produces a siphon or jet action, which permits a free flow of fuel from the nozzle. The fuel thus discharging is thoroughly mixed with the air as the high velocitv of same tends to break up the spray and reduce it to a gas.

that the richness of the mixture 42 nseaoaa As the comparatively low vacuum in the float chamber at this period does not restrict the fuel flow through the nozzle, it can therefore be seen that the richest mixture possible is obtained at this time period. An increase or speed after the 1 engine has started caused by opening the throttle valve immediately increases the vacuum and also the air velocity throughthe tube 15. The vacuum in the float chamber increasing at .a proportional rate has a tendency to restrict the dischar e through the fuel nozzle and therefore lessens the quantity of fuel discharging, thereby weakening the mixture. A still further increase in engine velocity produces vacuum within the carbureter of such intensity that the main air valve 9 opens against the tension of the spring 10, thus relieving the vacuum and also permitting a greater quantity oi air to pass through to the cylinders. Any increase or decrease the vacuum is, however, always imparted to the float chamber, thereby automatically regulatingthe discharge of the spray nozzle in proportion to the air volume passing through the carbureter.

The vent 17 not only serves the purpose of partly relieving the state of vacuum obtained Within the float chamber, but, at the same time, serves the purpose of an auxiliary air valve. The air thus admitted passes entirely around the float chamber and finally enters the mixing chamber through the vent 16 Where it is permitted to mix With the fuel and air from the nozzle and the main inlet 8.

The provision of the pipe 15 is also an important feature, as it Will at all times direct a current of air under high velocity around the mouth of the spray nozzle, in this manner not only increasing the suction at this point, but also serving as an efficient means to thoroughly break up the fuel ad mitted.

Under actual Working conditions it is found that the present attachments not only produce a better mixture-of fuel and air, but also make it possible to successfully operate over a greater range of engine speed and varying load than is otherwise possible. For

instance, it is possible to run the engine from an idling-point to a full load Without changing the adjustment, there being no appreciable loading of manifold at idlingspeed after running during as long a period as fifteen minutes or more. The rich mixture always obtained during low speeds Whether idling or under full load and a proportionately weak mixture is obtained the engine speed increases. 1

I wish it understood that various changes in the'torm, proportions and minor details of construction may be resorted to within the scope of the appended claim, and that I do not Wish to limit myself to the specific design and construction here shown.

Having thus described my invention, "What I claim and desire to secure by Letters Patent is A. carbureter comprising a mixing chamber through which air is drawn from the exterior, a float chamber surrounding the mixing chamber, a spray nozzle for the mixing chamber through which fuel is drawn from the float chamber, valve controlled orifice opening into the float chamber from the exterior for supplying air thereto above the normal level of the fuel, the Wall between the float and mixing chambers being provided with an aperture positioned above the normal level or" the fuel in the float chamber for applying suction to the latter to assist in drawing fuel into the same, a spring pressed valve. for maintaining the entrance to the mixing chamber closed under periods of low suction, and an open tube extending "from the exterior of the mixing chamber to a point adjacent the spray nozzle for supplying air to the latter for the purpose stated, the aperture in the wall being positioned so that air entering through the tube will sweep past said aperture.

lln testimony whereof l have hereunto set my hand in the presence of two subscribing vitnesses.

E. WlCl-iE tSHAllCl.

Witnesses 2 W. P. FnReUssoN,

W. Frisian. 

